Abstract
The structural and electronic properties of small Cu clusters were studied using density functional theory (DFT) calculations. The Cu clusters consist of up to fifty-five atoms with linear, planar, and three-dimensional structures. Five functionals, the Perdew-Wang 91 form of the generalized gradient approximation (PW91), Perdew-Burk-Ernzerhof functional (PBE), and three Minnesota functionals (M05, M06, and M06-L) were used. The dispersion correction in the format of DFT-D3 was also taken into account to the results of the PBE. The binding energy, average bond length, magnetic moment, and the HOMO-LUMO gap of each cluster were obtained and compared. DFT results for PBE and PW91 are very similar and agree with experimental data well. DFT-D3 corrections have no effect on the stable sequence. The copper clusters are more stable in the planar structure for clusters with n≤6, which agrees with other theoretical studies. In the case of bigger clusters, different DFT methods predicted different most stable structures. As cluster size increases, there was a monotonic decrease in magnetic moment for the odd number of clusters. As the linear cluster size increases, the bond distances between the atoms begin to alternate.